RF chip test method

ABSTRACT

An RF chip test method is disclosed. The RF chip test method includes disposing an RF chip within a chip socket, with the RF chip having at least one RF pin and at least one non-RF pin, the chip socket having conductive elements, and the conductive elements contacting the RF pin and the non-RF pin; connecting the non-RF pin to a ground end and connecting the RF pin to an RF measuring instrument; measuring a S11 parameter of the RF pin using the RF measuring instrument; and comparing the S11 parameter with an allowable range so as to judge the contact condition between the RF pin and the conductive element.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a chip test method, and moreparticularly to an RF chip test method.

2. Description of the Prior Art

Chip tests are typically performed during semiconductor chip productionprocesses to ensure the quality of electrical characteristics of thesemiconductor chips being fabricated. FIG. 1 is a schematic diagramcorresponding to a prior-art chip test process. A chip 50 is disposedwithin a chip socket 110. The chip 50 has at least one non-RF pin 51 andat least one RF pin 52. The chip socket 110 is disposed on a test board120. The test board 120 has at least one test circuit. The chip socket110 has a plurality of conductive elements 130. The press mechanism 70moves downward to make the conductive elements 130 contact the non-RFpin 51 and the RF 52 pin tightly.

Generally, when performing the chip test process of the chip 50, a DCopen/short test will be performed first to ensure the contact conditionbetween the non-RF pin 51 and the conductive elements 130. The electricresistance of the non-RF pin 51 is measured by a DC source so as toensure the properties of ESD protecting diode of the chip 50. Whenperforming the DC open/short test, the direct current is provided by adigital power source (DPS) or a precise measure unit (PMU), and theelectric resistance is calculated using the measured voltage.

The chip test process of the RF pin 52 is a high frequency analog test.When the RF pin 52 and the chip socket 110 has a bad contact condition,high frequency parasitic capacitance and parasitic inductance will beformed between the RF pin 52 and the chip socket 110. Moreover, the chiptest result of the RF pin 52 will be affected by the high frequencyparasitic capacitance and parasitic inductance. Therefore, the contactcondition between the RF pin 52 and the chip socket 110 should beensured before the high frequency analog test of the RF pin 52.

In the conventional chip test machine, the RF pin 52 is connected to anRF measuring instrument. The RF pin 52 is not connected to a DC source(DPS/PMU) that is able to perform the DC open/short test. In order toperform the DC open/short test of the RF pin 52, RF relays must bedisposed on the test board 120 for switching the RF pin 52 to the DCsource (DPS/PMU) or the RF measuring instrument. When performing the DCopen/short test, the RF pin 52 is connected to the DC source (DPS/PMU).When performing the high frequency analog test, the RF pin 52 isconnected to the RF measuring instrument.

However, there are some disadvantages associated with the RF relays. TheRF relays have to use the space of the test board 120, the cost of theRF relay is high, the working life of the RF relay is short, and it isnecessary to change RF relays frequently in mass production contexts.Therefore, the cost of the RF chip test is increased.

As a consequence of RF relays increasing the high frequency parasiticcapacitance and parasitic inductance of the test circuit of the testboard 120, chip test results are adversely affected by high frequencyparasitic capacitance and parasitic inductance. Therefore, the testresult of the RF chip is not stable.

Besides, in order to make the chip test result stable, the total chiptest time is increased because it is necessary to add delay time afterswitching the test circuits by the RF relays. Therefore, the efficiencyof the RF chip test process is low.

For reasons including the disadvantages of the prior art mentionedabove, there is a need to propose a novel RF chip test method. Use ofsuch an RF chip test method should vitiate the need to use RF relays totest the contact condition between RF pins and the chip socket.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made in order to meet needsincluding that described above, and it is an object of the presentinvention to provide an RF chip test method responsive to this need. Byusing the RF chip test method, use of RF relays for testing the contactcondition between RF pins and the chip socket can be eliminated.

In order to achieve the above objects, the present invention provides anRF chip test method. The RF chip test method includes disposing an RFchip within a chip socket, wherein the RF chip has at least one RF pinand at least one non-RF pin, the chip socket has a plurality ofconductive elements, and the conductive elements contact the RF pin andthe non-RF pin; connecting the non-RF pin to a ground end and connectingthe RF pin to an RF measuring instrument; measuring a S11 parameter ofthe RF pin using the RF measuring instrument; and comparing the S11parameter with an allowable range so as to judge the contact conditionbetween the RF pin and the conductive element.

The RF chip test method of the present invention is capable of testingthe contact condition between RF pins and the chip socket without RFrelays. The test result of the RF chip is stable, and the efficiency ofthe test process is also increased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a chip test process according to theprior art;

FIG. 2 shows a flow diagram of an RF chip test method in accordance witha preferred embodiment of the present invention;

FIG. 3 shows an electrical diagram corresponding to the RF chip testmethod;

FIG. 4 shows the S11 parameters of the same RF pin of the same RF chip,with the RF pin and the conductive element having a good contactcondition;

FIG. 5 shows the S11 parameters of the same RF pins 52 of differentchips, with the RF pins and the conductive elements having a goodcontact condition;

FIG. 6 shows the S11 parameters of the same RF pin of the same chip,with the RF pin and the conductive element having a bad contactcondition;

FIG. 7 shows the S11 parameters of the same RF pins 52 of the differentchips, with the RF pins and the conductive elements having a bad contactcondition;

FIG. 8A shows the S11 parameters of a specific frequency 4.2 GHz of RFpins of different chips, wherein the RF pins and the conductive elementshave a good contact condition; and

FIG. 8B shows the S11 parameters of the specific frequency 4.2 GHz of RFpins of different chips, wherein the RF pins and the conductive elementshave a bad contact condition.

DETAILED DESCRIPTION OF THE INVENTION

The detailed description of the present invention will be discussed inthe following embodiments, which are not intended to limit the scope ofthe present invention and which can be adapted for other applications.While the drawings are illustrated in detail, it is appreciated that thequantity of the disclosed components may be greater or less than thatdisclosed with the exception of contexts expressly restricting theamount of the components.

FIG. 2 shows a flow diagram of an RF chip test method 300 in accordancewith a preferred embodiment of the present invention. The RF chip testmethod 300 includes the following steps.

First, with reference to FIG. 1, the performance of step 310 comprisesdisposing a chip 50 within a chip socket 110. The chip 50 has at leastone non-RF pin 51 and at least one RF pin 52. The chip socket 110 isdisposed on a test board 120. The test board 120 has at least one testcircuit. The chip socket 110 has a plurality of conductive elements 130.The conductive elements 130 contact the non-RF pin 51 and the RF 52 pinrespectively.

FIG. 3 shows an electrical diagram corresponding to the RF chip testmethod. Performing step 320 comprises connecting the non-RF pin 51 to aground end 121 and connecting the RF pin 52 to an RF measuringinstrument 180. In this embodiment, the RF measuring instrument 180 is aVector Network Analyzer. The Vector Network Analyzer is a measuringdevice used for analyzing the frequency-domain response. The VectorNetwork Analyzer is capable of presenting information (the properties)using a scattering-parameter paradigm.

With continued reference to FIG. 2, performance of step 330 comprises aS11 parameter (return loss) of a specific frequency of the RF pin 52being measured using the RF measuring instrument 180. Because theoperating voltage of each chip 50 may be different, connecting thenon-RF pin 51 to a ground end 121 is suitable for each chip 50. Therewill be no risk that the chip 50 may be damaged. The S11 parametermeasured is the physical properties of the transistor in the off stagecondition.

FIG. 4 shows the S11 parameters of the same RF pin 52 of the same RFchip 50, with the RF pin 52 and the conductive element 130 having a goodcontact condition.

The S11 parameters can be measured using the following steps: disposinga chip 50 within a chip socket 110; connecting the non-RF pin 51 of thechip 50 to a ground end and connecting the RF pin 52 to a Vector NetworkAnalyzer; measuring a S11 parameter (return loss) of the RF pin 52,wherein the upper limit of the frequency range for measuring the S11parameter can be the working frequency of the chip 50 and the lowerlimit of the frequency range for measuring the S11 parameter can be 1GHz below the working frequency of the chip 50; removing the chip 50;and repeating the steps mentioned above.

When the RF pin 52 and the conductive element 130 have a good contactcondition, the S11 parameters concentrate on one value. In thisembodiment, the S11 parameters of the same RF pin 52 have the minimumvalue at the frequency 4.2 GHz. Therefore, 4.2 GHz is the specificfrequency of the RF pin 52.

FIG. 5 shows the S11 parameters of the same RF pins 52 of differentchips 50, with the RF pins and the conductive elements having a goodcontact condition.

When the RF pins 52 of the different chips 50 and the conductive element130 have a good contact condition, the S11 parameters also concentrateon one value. In this embodiment, the S11 parameters of the RF pins 52have the minimum value at the frequency 4.2 GHz. Therefore, 4.2 GHz isthe specific frequency of the RF pin 52 of the chips 50.

FIG. 6 shows the S11 parameters of the same RF pin 52 of the same chip50, with the RF pin 52 and the conductive element 130 having a badcontact condition. The S11 parameters have been measured five times.When the RF pin 52 and the conductive element 130 have a bad contactcondition, the S11 parameters of the same chip 50 do not concentrate onone value, and the S11 parameters of frequency 4.2 GHz are larger thanthe S11 parameters of the good contact condition.

FIG. 7 shows the S11 parameters of the same RF pins 52 of the differentchips 50, with the RF pins 52 and the conductive elements 130 having abad contact condition. The S11 parameters have been measured ten times.When the RF pins 52 and the conductive elements 130 have a bad contactcondition, the S11 parameters of different chip 50 do not concentrate onone value, and the S11 parameters of frequency 4.2 GHz are larger thanthe S11 parameters of the good contact condition.

FIG. 8A shows the S11 parameters of the specific frequency 4.2 GHz of RFpins 52 of different RF chips 50, wherein the RF pins 52 and theconductive elements 130 have a good contact condition. When the RF pins52 and the conductive elements 130 have a good contact condition, theS11 parameters concentrate on one value. The average value of the S11parameters is −8.355, and the standard deviation value is 0.167.

When the S11 parameters are distributed in normal distribution, theaverage value plus/minus 3 times of the standard deviation value cancover 99.75% range of the S11 parameters. In this embodiment, theallowable range has an upper limit which is the average value plus threetimes of the standard deviation value. The upper limit is −7.853 in thiscase. Moreover, the allowable range does not have a lower limit becausea smaller S11 parameter indicates that the return loss is smaller.

Finally, performing step 340, the S11 parameter is compared with anallowable range so as to judge the contact condition between the RF pin52 and the conductive element 130.

FIG. 8B shows the S11 parameters of the specific frequency 4.2 GHz of RFpins 52 of different RF chips 50, wherein the RF pins 52 and theconductive elements 130 have a bad contact condition. When the RF pins52 and the conductive elements 130 have a bad contact condition, the S11parameters do not concentrate on one value and the S11 parameters arenot within the allowable range. Therefore, it is possible to judge thecontact condition between the RF pin 52 and the conductive element 130by comparing the S11 parameter with the allowable range mentioned above.

For example, when the S11 parameter is within the allowable range, theRF pins 52 and the conductive element 130 have a good contact condition.When the S11 parameter is not within the allowable range, the RF pins 52and the conductive element 130 have a bad contact condition.

By using the RF chip test method of the present invention, testing ofthe contact condition between RF pins and the chip socket without RFrelays becomes possible. The test result of the RF chip is stable, andthe efficiency of the test process is also increased.

Although specific embodiments have been illustrated and described, itwill be appreciated by those skilled in the art that variousmodifications may be made without departing from the scope of thepresent invention, which is intended to be limited solely by theappended claims.

1. An RF chip test method, comprising: disposing an RF chip within achip socket, wherein said RF chip has at least one RF pin and at leastone non-RF pin, the chip socket has a plurality of conductive elements,and said conductive elements contact said RF pin and said non-RF pin;connecting said non-RF pin to a ground end and connecting said RF pin toan RF measuring instrument; measuring a S11 parameter (return loss) of aspecific frequency of said RF pin using said RF measuring instrument;and comparing said S11 parameter with an allowable range so as to judgethe contact condition between said RF pin and said conductive element.2. The RF chip test method according to claim 1, wherein said measuringdevice is a Vector Network Analyzer.
 3. The RF chip test methodaccording to claim 1, wherein when said RF pin and said conductiveelement have a good contact condition, the frequency of the minimumvalue of said S11 parameter is said specific frequency.
 4. The RF chiptest method according to claim 1, wherein when said RF pin and saidconductive element have a good contact condition, said allowable rangeis determined by an average value and a standard deviation value of aplurality of said S11 parameters of said RF chip.
 5. The RF chip testmethod according to claim 1, wherein said allowable range has an upperlimit and said upper limit is said average value plus three times ofsaid standard deviation value.
 6. An RF chip test method, comprising:measuring a S11 parameter (return loss) of a specific frequency of an RFpin of an RF chip, wherein said RF pin and a chip socket have a goodcontact condition and the frequency of a minimum value of said S11parameter is said specific frequency; measuring an allowable range ofsaid RF pin of a plurality of RF chips, wherein said RF pin and saidchip socket have a good contact condition, said allowable range isdetermined by an average value and a standard deviation value of aplurality of S11 parameters of said RF chip; disposing another RF chipwithin said chip socket, wherein said another RF chip has at least oneRF pin and at least one non-RF pin; connecting said non-RF pin to aground end and connecting said RF pin to an RF measuring instrument;measuring a S11 parameter (return loss) of said specific frequency ofsaid RF pin by said RF measuring instrument; and comparing said S11parameter with said allowable range so as to judge the contact conditionbetween said RF pin and said chip socket.
 7. The RF chip test methodaccording to claim 6, wherein said RF measuring instrument is a VectorNetwork Analyzer.
 8. The RF chip test method according to claim 6,wherein said allowable range has an upper limit and said upper limit issaid average value plus three times of said standard deviation value. 9.An RF chip test method, comprising: measuring a specific frequency of anRF pin of an RF chip; measuring an allowable range of said RF pin of aplurality of RF chips; disposing another RF chip within said chipsocket, wherein said another RF chip has at least one RF pin and atleast one non-RF pin; connecting said non-RF pin to a ground end andconnecting said RF pin to an RF measuring instrument; measuring a S11parameter (return loss) of said specific frequency of said RF pin usingsaid RF measuring instrument; and comparing said S11 parameter with saidallowable range so as to judge a contact condition between said RF pinand said chip socket.
 10. The RF chip test method according to claim 9,wherein said RF measuring instrument is a Vector Network Analyzer. 11.The RF chip test method according to claim 9, wherein when said RF pinand said chip socket have a good contact condition, the frequency of theminimum value of said S11 parameter is said specific frequency.
 12. TheRF chip test method according to claim 9, wherein when said RF pin andsaid chip socket have a good contact condition, said allowable range isdetermined by an average value and a standard deviation value of aplurality of said S11 parameters of said RF chip.
 13. The RF chip testmethod according to claim 12, wherein said allowable range has an upperlimit and said upper limit is said average value plus three times ofsaid standard deviation value.